js input text box to enter the character limit shown how many characters you can enter

This article describes js text box to enter the word limit, dynamic display of words you can enter the number of words can also enter the prompt, a friend in need can refer to.

代码如下:
<input name="title" type="text" size="50" value="{$p.title}" maxlength="15" onkeyup="javascript:setShowLength(this, 15, 'cost_tpl_title_length');">

<Span class = "red" id = "cost_tpl_title_length"> can also enter words 15 </ span> 

js code as follows:

function setShowLength(obj, maxlength, id) {
 var rem = maxlength - obj.value.length;
 var wid = id;
 if (rem < 0){
 rem = 0;
 }
 document.getElementById(wid).innerHTML = "还可以输入" + rem + "字数";
}